Scientists have found traces of the tough material that once formed the outer shells of ancient sea creatures called trilobites preserved in fossils more than 500 million years old.

This discovery shows that some living organisms can survive much longer on Earth. rock It has changed the way scientists think about how carbon is stored deep in the Earth over long periods of time, much more than experts once believed.

Finding chitin from fossils

Researchers discovered fossils of this type of trilobite inside a layer of shale near Death Valley in eastern California. OlenellasAn extinct marine animal that lived on the ocean floor more than 500 million years ago, with small pieces of its original shell still intact.

Laboratory research at the University of Texas at San Antonio (UTSA) elicited distinct chemical signals from its shell patches.

UTSA Earth and Planetary Scientist Elizabeth Bailey linked the signal to a shell polymer that had been missed in previous searches.

The discovery of chitin, even if only a few fossils, suggests that some fossils exist. carbon-Rich compounds can remain trapped even under normal burial conditions.

modern crab shell And insect skin relies on chitin, a tough sugar-based substance found in many integuments, to keep it firm and light.

Cells bind chitin into long chains and pack it into fibers that are resistant to tearing and do not dissolve easily.

“However, chitin is considered the second most abundant natural polymer on Earth, after cellulose,” Dr. Bailey said. There are so many things that life creates chitinits rate of decay determines whether organic carbon is immediately cycled or remains buried longer.

Why does corruption stagnate?

Under normal ocean floor conditions, bacteria and fungi attack chitin immediately after death and use enzymes to cleave it.

In the ocean and soil, enzymes produced by microorganisms cleave chitin chains to create tiny sugars that cells can consume.

Typically, the heat and pressure during burial rearranges these molecules, leaving behind nothing more than a carbon film or a copy of the mineral.

This history makes concerns about contamination real, so any positive signal will have to clear a high bar.

Checks behind the bill

To rule out modern contamination, the UTSA team looked for chemical fingerprints that only appear when old polymers remain.

With fluorescent staining, fossil The material shined, and two follow-up chemical checks confirmed the same signature.

The study used infrared and mass spectrometry to detect chitin components, strengthening the identification.

Burial history likely influenced the results, since even if shells remain, high temperatures and circulating fluids can erase traces of organic matter.

stones that protect

Minerals penetrate into minute gaps, shellIt then hardens, preventing water and microorganisms from reaching the polymer.

Most microorganisms require oxygen to continue breaking down molecules, so when rock seals the shell, oxygen is reduced and decay is slowed.

A similar chemical reaction was discovered in Cambrian sponges, paper We linked its survival to rapid mineral sealing.

Long-term survival should never be assumed, as small changes in temperature, pressure, and groundwater flow can erase the same polymer.

carbon trapped in stone

Much of the Earth’s carbon ends up in rock, and U.S. geology investigation Please note that sinks can be stored for long spans.

Buried remains can avoid complete decomposition, after which pressure turns the sediment into rock, keeping some of its carbon out of the air.

Chitin transports both carbon and nitrogen, enhancing carbon sequestration and storing carbon from the atmosphere in layers over long periods of time.

“Our results show that chitin has persisted in the geological record much longer than originally thought,” Bailey said.

limestone in the loop

Limestone is formed when marine artifacts pile up and harden, leaving behind a thick layer of limestone. layer People are also cut out as stone.

In the bodies of many shell-building animals, chitin acts as a flexible framework, allowing carbonate deposits to fill it with minerals.

In addition to calcium carbonate shells, these deposits may also trap chitin debris, adding even more organic carbon to the limestone.

Still, natural burials operate on long-term scales and cannot counter today’s rapid increases in carbon dioxide.

when the rock gets hot

Burials can warm and compress rocks, causing metamorphism, where heat and pressure change rocks over time.

Higher temperatures can break long chains and replace minerals, leaving no clear trace of the original polymer.

However, Carrara’s shell still transmits the signal after mild heating, indicating that chitin can survive longer than chemistry predicts.

Mapping that breaking point will require not only well-preserved shells, but also fossils from hotter environments and different rock types.

Lessons learned from this chitin fossil

In addition to trilobites, many fossils also have thin organic layers hidden in them, and now we can check for chitin residues in those layers.

By comparing similar shells across different burial histories, UTSA researchers could help reveal when chitin survives and when it transforms into simple carbon.

Finding chitin with mineral grains also helps paleontologists distinguish the original biology from later changes during fossilization.

Careful management remains important, as modern organic residues can creep into cracks and blur the line between old and new.

That chitin survived in one ancient shell shows that the rock record can preserve more biology than expected.

Tracking where that polymer lingers and where it disappears will provide accurate estimates of the carbon cycle and guide future fossil research.

This study Palaios.

Photo: АП/Hong Kong Antiquities and Monuments Department

—–

Like what you read? Subscribe to newsletter We bring you fascinating articles, exclusive content, and the latest updates.

Please check it out earth snapThis is a free app provided by. Eric Ralls and Earth.com.

—–